Water tube boiler



Nbv. 7, 1967 H. D. WATSON ETAL WATER TUBE BOILER 4 Sheets-Sheet 1 Filed May 21, 1965 INVEHTONS find/ W16 Mm:

kr'roameys H. D. WATSON ETAL 3,351,041

Nov. 7, 1967 WATER TUBE BOILER 4 Sheets-Sheet 2 Filed May 21. 1965 O ocoOoOoooOu Imam- R3 Ar-roRNEY 5 H. D. WATSON ET AL 3,351,041

Nov. 7, 1967 WATER TUBE BOILER 4 Sheets-Sheet 3 Filed May 21, 1965 7 I #J 0000 9 2! W a m a 7 m5 c w .L w M W 0 x J 3 o lNvzN-roas X4, 10M mm M 3y 65m, (14/, xitz al. 1/4500 ATToRNEYS Nov. 7, 1967 i H. D. WATSON ETAL 3,351,041

WATER TUBE BOILER Filed May 21. 1965 4 Sheets-Sheet 4 V luvanllofis W fiwza aw A {Md 36;! mm) 3/ I 7 who, 64/ ,Jaww *1/25) A-r-HSRN ys United States Patent 3,351,041 WATER TUBE BOILER Henry Daniel Watson, Chorley Wood, and Edward Cecil Richardson, London, England, assignors to Mitchell Engineering Limited, London, England, a company of Great Britain Filed May 21, 1965, Ser. No. 458,839 19 Claims. (Cl. 122250) ABSTRACT OF THE DISCLOSURE A water tube boiler in which water to be heated is circulated consecutively through three nested helically wound coil tubes, the convolutions of the two inner coils being in contact over the greater part of the lengths of the coils and spaced apart at alternate ends thereof, and which boiler has an air inlet where there is situated a burner for heating air pumped to the inlet and an outlet for products of combustion at the opposite end of the furnace adjacent which there is mounted a deflector which ensures that the heated air circulates past all the helical coils before passing through the outlet.

This invention comprises improvements in or relating to water tube boilers.

According to the present invention, a water tube boiler comprises a furnace casing mounted on a base, and having an air inlet at one end and an outlet for products of combustion at the other end, means for delivering fuel through the inlet to be burnt with the air, at least three nested and spaced helical tube coils connected together in series and disposed Within the casing with their axes extending between said inlet and outlet and each of which coils is wound as a simple helix so that water or steam may flow through all its convolutions in the same direction, at least the two innermost coils of which nested coils each have their convolutions in direct contact over a substantial portion of their length so that the gases flowing into and through the innermost coil sweeps over a sinuous surface provided by its contacting convolutions and then flows in the opposite direction between outer surface of the innermost coil and the next helical coil outside it and again changes direction in flowing between the last mentioned helical coil and the next coil outside it.

According to another aspect of the invention a water tube boiler comprises a furnace casing mounted on a base and having an air inlet at one end and an outlet for products of combustion at the other end, means for delivering fuel through the inlet to be burnt with the air, at least-three nested and spaced helically wound tube coils connected together in series and disposed within the casing with their axes extending between said inlet and outlet, which nested coils have certain of their convolutions in contact and others spaced apart so that the hot gases after flowing through a space bounded by convolutions in contact pass through spaces between spaced convolutions into a surrounding space, change their direction, and flow past other convolutions.

In one arrangement, the innermost helix has said spaced convolutions at its upper end and the next helix outside it has spaced convolutions at its lower end.

In another arrangement, the convolutions of the innermost helix are in contact throughout the helix length and the helix next outside it has said spaced convolutions at its lower end.

The casing may be surrounded by a cooling jacket through which air passes to said inlet, and the convolutions of the outermost helix may be spaced apart over a major part of the length of the helix, and the convolutions spaced away from the air-cooled casing, or they may be in contact throughout the length of the helix which is arranged in contact with the air-cooled casing substantially over its whole length.

The boiler may also comprise steam superheating tubes disposed in the combustion gas path and connected with a steam separator receiving Wet steam from the water tubes.

According to a feature of this invention, the water tube boiler may be provided with a steam tube wound spirally to lie on a surface of a cone, adjacent said outlet the convolutions being in contact thereby to close the upper end of the space within the two innermost helices, but leaving a central opening provided with a door to relieve furnace explosions which steam tube is connected to one of the helical coils. The conically wound steam tube is preferably connected to the innermost helical coil so that fluid flows from the latter into the conically wound steam tube.

Also air heaters, or economisers may be arranged in the combustion gas path.

A duplex fuel burner may be disposed within said air inlet and valve means are provided whereby one or other of said burners is rendered operative.

The furnace casing may be provided at one end with a removable cover and said coils are provided with disconnectable connections whereby they may be withdrawn from the end of the casing when the cover is withdrawn.

The coils may be connected together in. series by headers outside said casing and said headers are connected through joints in a wall of the casing to ends of the coils Within the casing.

As indicated above the casing of the furnace may be air-cooled and the air used for cooling the casing is fed to the air inlet. For instance the casing may be doublewalled and an air supply may be passed downwardly through the space between the walls by a blower or extractor fan, the air flowing from this space to the air 11'] et.

Preferably in any of the arrangements referred to above the casing is a vertically disposed cylinder and the air inlet may be arranged at the bottom thereof and the outlet at the top or vice versa.

The various coils maybe provided with drainage cocks so that the boiler may be self drained. According to this invention in another aspect, there is provided the combination with a water tube boiler as above set forth, of a mounting base whereon the boiler is supported on pillars, a fan for supplying air for cooling the furnace casing and to the air inlet, or a fan for exhausting combustion gases, a feed water pump, and a motor for driving the fan and pump, the fan, the pump and the motor, with or without ancillary equipment, being secured on said base, the combination constituting a steam generating plant capable of transportation as a unit.

The fan, the pump and the motor may be disposed, in part at least, below the boiler. If an induced draught fan is used it is preferably located below the boiler. This arrangement facilitates transportation of steam generating plant over rough terrain. To improve transportation in these circumstances, the packaged steam generating plant may comprise a framework extending from the base along one side of the water boiler and including skid members whereon the plant may rest during transportation or movement of the plant.

Some constructions of steam plant incorporating the above and other features of invention will now be described in detail with reference to the accompanying diagrammatic drawings in which:

FIGURE 1 is a vertical section through one construction of transportable packaged steam generating plant;

FIGURE 2 is a corresponding view of a second construction;

FIGURE 3 is an elevation in half section of a third construction; and

FIGURE 4 is a diagrammatic vertical section through a fourth construction omitting the water and air pump.

The plant shown in FIGURE 1 comp-rises a mounting base 1% including a girder framework of which longitudinal members 11 constitute skids for transportation purposes.

The plant also comprises a boiler supported on pillars 12 in spaced relation to the base 10.

The boiler is cylindrical and comprises a doublewalled casing 13 having a centrally disposed air inlet 14 at its lower end and at its upper end a chimney 15 mounted centrally on a removable top 15a. The air inlet 14 is fed with air through ducting 16 which communicates with the space 13a between the walls of the casing 13, the space 13a being fed with air through ducting 19 by a forced draught fan 17 driven by a motor 18. The air from ducting 19 enters the space 13a at its upper end and circulates around the space before entering the ducting 16.

The plant is fed with fuel to be burnt with the air, the fuel delivery means being below the boiler. In the form illustrated gaseous and liquid fuel are fed to a burner 20 disposed centrally of the inlet 14, gaseous fuel being supplied through pipe 21 and liquid fuel through pipe 22, The pipe 21 has a branch 23 leading to a pilot burner 24. The burner 20 may be duplicated so that one may be in ope-ration while the other is being serviced.

The boiler is of the water tube type and has a spiral water tube arrangement. The water tube comprises three helically wound tube coils 25, 26, 27 disposed one inside the other in radially spaced relation.

The outermost helix 27 has its convolutions in contact with the inner wall of the casing 13, and water is fed to the upper end of this helix from an inlet header 28 receiving water from a feed pump 29 through pipe 30. The pump 29 is driven by the motor 18. The lower end of the helix 27 is connected by pipe 27a to an intermediate header 31 which is in turn connected by pipe 26a to the lower end of the helix 26. The header 31 is immediately below the bottom wall 13b of the casing and the connecting pipes 26a, 2711 are provided with readily disconnectable joints 26b, 2712 so that the header 31 may be separated from the helices 26, 27.

The helix 26 has its lowermost convolutions in spaced relation and its upper convolutions in contact with one another, and the uppermost convolution lies against the circumference of a conical internal roof 34 provided with a hinged central explosion door 35. The upper end of helix 26 is disconnectably coupled by a joint 26d to a pipe 26c which in its turn is connected to a joint 26e to an intermediate header 36, the arrangement being such that by loosening the joint 26c and disconnecting the joint 26d the upper end of the coil 26 is disconnected from the top and the pipe 260 swung clear of the top.

A pipe 37 leads downwardly from header 36 to a further header 38 disposed below the boiler and a pipe a including a disconnectable joint 25b connects the header 38 to the lower end of the helix 25. The lowermost convolutions of the helix 25 are in contact and the upper convolutions are spaced apart.

The internal roof 34 is lined with a spirally wound steam tube 39 which may constitute a superheater and which is connected at its larger diameter end with the upper end of the helix 25 and at its smaller diameter end with a steam outlet tube 41) leading to a steam separator 41 having a steam outlet connection 42 containing a control cock 43.

By virtue of this tube arrangement, the combustion gases produced by burning of fuel in the space 44 flow upwardly in this space and then downwardly between helices 25, 26 and then upwardly between helices 26, 27

to the chimney. The helix 27 protects the casing walls, which are also air-cooled, so that the use of a firebrick, or like lining is unnecessary.

The headers 31, 36, 38 and the steam separator 41 have drain cocks 45 and the pipe 40 has an air cock 40a whereby the tube arrangement may be completely selfdraining and flushing is facilitated when this is necessary, any deposit within the tubes being washed out through the cocks 43 of the headers 31, 38. Also since the boiler top 15a is completely removable and the connections to the headers contain disconnectable joints, the helices are readily replaceable.

A similar arrangement is shown in FIGURE 2 in which references as used in FIGURE 1 are again employed to indicate like parts.

In this construction, however, there are a plurality of water preheating inlet helices 127 between the headers 28 and 31, and steam superheater coils 50 are disposed between the helices 25, 26, these coils being supported on pillars 51.

The helix 25 has its convolutions in contact throughout the length of the helix, but as before the helix 26 has its lowermost convolutions spaced apart.

Another and similar arrangement, which however requires a smaller area base 10, is shown in FIGURE 3. In this arrangement, the pillars 12 are of such height as to allow the motor 18, fan 17, feed water pump 29, a control gear casing 60 and other ancillary equipment to be located below the boiler.

The two innermost helically wound water tube coils 25, 26 are as in FIGURE 2, and the outermost helically wound tube coil 227 is spaced inwards from the casing 13 and has some of its convolutions in contact and others spaced apart. A refractory lining 61 is provided for the lower part of the casing 13.

Also for transportation, the plant is turned on its back and slides on a pair of skids 62 which are longitudinal members of a framework 63 which extends across the back and partly across the sides of the plant when it is standing on its base 10.

The arrangement shown in FIGURE 4 is somewhat similar to that of FIGURE 2 but with furnace casing and air cooling jacket 13 and air inlet 14 and outlet to chimney 15 inverted.

The water enters at 61 and flows downwardly through the helical preheating coils 127 the lower end of which are connected by the pipes 127a to a header beneath the bottom of the furnace casing. The header is provided with a drainage cock 45 and with an upwardly extending pipe 61 leading to the bottom end of the intermediate helical coil 26. The upper end of this coil is connected by a pipe 62 which extends downwardly outside the casing and is connected to the lower and smaller end of the spiral helical coil 39. The lowest part of the pipe 62 is provided with a drainage cook 45. The lower end of this is provided with a central opening closed by the hinged explosion door 35. The upper end of this latter coil is connected by a pipe 63 with the lower end of the innermost helical coil 25 and the upper end terminates in a spiral helical coil 25a having a central opening at its upper and smaller end opposite the inlet 14. The upper end of this coil is connected by a pipe with a steam separator 41. As in the construction of FIGURE 2 superheater pipes 50 are disposed in the space between the helical coils 25 and 26 and are fed with steam from the steam separator by a pipe 65 and superheated steam leaves them through the pipe 66.

Duplex oil burners are directed into the air inlet 14 which latter receives air from a cowl 67 communicating with upper end of the air jacket 13a the lower end of which receives air from an impeller (not shown). The air impeller and a pump for the water both driven from the same motor are mounted on the base or carriage 10.

The lower end of the furnace casing is also provided with a cowl 68 which communicates with a chimney.

The hot products of combustion flow downwardly through the innermost helical coil all the convolutions of which contact with one another. They flow out of the lower end thereof and up through the space between the helicals 25, 26 and past the superheater coils. They then pass through spaces between the convolutions at the upper end of the helical coil 26 and downwardly between the remaining convolutions of that coil which contact with one another and between the convolutions of the coils 12.7 and finally pass into the cowl 68.

The cowl 67 together with burners may be detachably secured to the upper end of the furnace casing and the coils so detaehably mounted in the bottom wall 13b that they may be removed from the top of the furnace.

We claim:

1. A water tube boiler comprising,

(a) a furnace casing mounted on a base and having an air inlet at one end and an outlet for products of combustion at the other end,

(b) means adapted to deliver fuel and air for combustion through the inlet,

(c) at least three nested and spaced helical tube coils connected together in series and disposed within the casing with their axes extending between said inlet and outlet, and each of which coils is wound as a helix, the outermost coil having all its convolutions in contact and the other coils having certain convolutions in contact throughout their circumferences and others spaced apart throughout their circumferences, the coil next to the outermost coil having spaced convolutions at the end adjacent the inlet of the furnace, and the next coil having spaced convolutions at the end adjacent the outlet of the furnace,

(d) a deflector means mounted within the furnace casing, opposite the outlet end thereof, and adapted to overlie the end convolutions of the helical coils other than the outermost coil to prevent a direct flow of the products of combustion through the outlet and to deflect the products of combustion between the helical coils, so that they pass from the space between the two outer coils, over the outside of the deflector means and through the outlet.

2. A water tube boiler according to claim 1 wherein said deflecting means is provided with a door opposite said outlet and adapted automatically to open upon build up of pressure within the furnace.

3. A Water tube boiler according to claim 1 wherein the deflector means comprises a spirally wound steam tube adapted to lie on an inwardly directed face of a conical plate and connected in series with the innermost coil.

4. A water tube boiler according to claim 3 wherein the innermost convolution of the spirally wound steam tube is provided with a central opening and the conical plate is provided with a central door adapted automatically to open upon build up of pressure within the furnace.

5. A water tube boiler according to claim 1 wherein the convolutions of the innermost helix are in contact throughout the helix length and the adjacent helix has said spaced convolutions at its lower end.

6. A water tube boiler according to claim 1 wherein the casing is surrounded by a cooling jacket through which air circulates and then passes to said inlet and wherein the convolutions of the outermost helix are spaced apart over a major part of the length of the helix, and the convolutions are spaced away from the air-cooled casing.

7. A water tube boiler according to claim 1 wherein the casing is surrounded by a cooling jacket through which air circulates and then passes to said inlet and wherein the convolutions of the outermost helix are in contact throughout the length thereof with the air-cooled casing substantially over its whole length.

8. A water tube boiler according to claim 1 wherein steam superheating tubes are disposed in the combustion gas path between the innermost and next helical coils and are connected to a steam outlet of a steam separator which receives wet steam from the water tubes.

9. A water tube boiler according to claim 1 wherein said casing is a vertically disposed cylinder having said inlet at the bottom thereof and the outlet at the top thereof and wherein said helical coils are co-axial with the axis of the cylinder.

10. A water tube boiler according to claim 1 wherein said casing is a vertically disposed cylinder having said inlet at the top thereof and the outlet at the bottom thereof and wherein said helical coils are co-axial with the axis of the cylinder.

11. A water tube boiler according to claim 1 wherein any of said coils are provided with drainage cocks.

12. A water tube boiler according to claim 2 wherein the outlet from said steam pipe is connected to a steam separator.

13. A Water tube boiler according to claim 1 wherein duplicate fuel burners are disposed obliquely to one another and with their outlets substantially coincident within said air inlet and valve means are provided whereby one or other of said burners is rendered operative.

14. A water tube boiler according to claim 1 wherein said furnace casing is provided at one end with a removable cover and said coils are provided with disconnectable connections whereby they may be withdrawn from the end of the casing when the cover is withdrawn.

15. A water tube boiler according to claim 11 wherein said coils are connected together in series by headers outside said casing and said headers are connected through joints in a wall of the casing to ends of the coils within the casing.

16. The combination with a water tube boiler as claimed in claim 1 of a mounting base wherein the boiler is supported on pillars, a fan for circulating air through the furnace, a feed water pump and a motor for driving the fan and pump, the fan, the pump and the motor being secured on said base, the combination constituting a steam generating plant capable of transportation as a unit.

17. The combintion according to claim 14 wherein the fan, the pump and the motor are disposed in part at least, below the boiler.

18. The combination according to claim 14 the fan Eeing an induced draught fan which is located below the o1 er.

19. The combination according to claim '14 further comprising a framework extending from the base along one side of the water boiler and including skid members where in the plant may rest during transportation or movement of the plant.

References Cited UNITED STATES PATENTS 1,047,893 12/1912 Korb 122250 2,360,891 10/1944 Powers et a1 122250 2,621,635 12/1952 Joosten 122250 2,823,652 2/1958 Mader 122-250 3,051,146 8/1962 Clarkson et al 122249 3,282,257 11/1966 Mclnerney et a1 122-250 FREDERICK L. MATTESON, 111., Primary Examiner. E. G. FAVORS, Assistant Examiner. 

1. A WATER TUBE BOILER COMPRISING, (A) A FURNACE CASING MOUNTED ON A BSE AND HAVING AN AIR INLET AT ONE END AND AN OUTLET FOR PRODUCTS OF COMBUSTION AT THE OTHER END, (B) MEANS ADAPTED TO DELIVER FUEL AND AIR FOR COMBUSTION THROUGH THE INLET, (C) AT LEAST THREE NESTED AND SPACED HELICAL TUBE COILS CONNECTED TOGETHER IN SERIES AND DISPOSED WITHIN THE CASING WITH THEIR AXES EXTENDING BETWEEN SAID INLET AND OUTLET, AND EACH OF WHICH COILS IS WOUND AS A HELIX, THE OUTERMOST COIL HAVING ALL ITS CONVOLUTIONS IN CONTACT AND THE OTHER COILS HAVING CERTAIN CONVOLUTIONS IN CONTACT THROUGHOUT THEIR CIRCUMFERENCE AND OTHERS SPACED APART THROUGHOUT THEIR CIRCUMFERENCES, THE COIL NEXT TO THE OUTERMOST COIL HAVING SPACED CONVOLUTIONS AT THE END ADJACENT THE INLET OF THE FURNACE, AND THE NEXT COIL HAVING SPACED CONVOLUTIONS AT THE END ADJACENT THE OUTLET OF THE FURNACE, 